A few more that I've been thinking about:
If you do implement a NSFW toggle, make the NSFW and NSFL toggles separate. One of my big issues with reddit is you can't enable porn without also enabling the kind of stuff that makes you want to quit reddit.
A way to exit from a post, the same as the back button, by swiping right. Like how infinity does it.
A button to suggest features or bugs to either the instance or devs.
More documentation for various things. In particular I'm curious if it's possible to run an instance without opening any ports on your router? Maybe using swag or tailscale-funnel?